Thanks for the update.
My guess is nuts were used to upgrade the defunct bolt put in the guy who rebuilt the entrance, Robert Bunting, sometime around 17 years ago!
On one occasion late last year,we found the entrance door open and clearly anyone could enter.
I secured it, using bolts, since, I felt kids could enter and may have an accident
Since I did not use any super glue on the the threads, I assume the land owner also did not like the idea of the door being open and remodified our work.